1. Field of the Invention
The present invention relates generally to laminated ultrasonic waveguides fabricated from sheet stock and a method of fabrication thereof, and more particularly pertains to laminated ultrasonic waveguides or blades fabricated from sheet metal stock and a method of fabrication thereof which extend the possible geometries of the ultrasonic waveguides or blades while reducing manufacturing costs and material waste.
2. Discussion of the Prior Art
Ultrasonic waveguides are utilized in many different technical fields, such as in ultrasonic medical instruments, including both hollow core and solid core instruments, which are well known in the art and are used for the safe and effective treatment of many medical conditions. Ultrasonic instruments, and particularly solid core ultrasonic instruments, are advantageous because they may be used to cut and/or coagulate organic tissue using energy in the form of mechanical vibrations at ultrasonic frequencies transmitted to a surgical end-effector. Ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels using a suitable end-effector, may be used to cut, dissect, or cauterize tissue. Ultrasonic instruments utilizing solid core technology are particularly advantageous because of the amount of ultrasonic energy that may be transmitted from the ultrasonic transducer through an ultrasonic waveguide (also known as a blade) to the surgical end-effector. Such instruments are particularly well suited for use in minimally invasive procedures, such as endoscopic or laparoscopic procedures, wherein the end-effector is passed through a trocar to reach the surgical site.
Ultrasonic surgical instruments and devices typically comprise an ultrasonic transducer which converts an electrical signal to oscillatory motion, an ultrasonic waveguide, and an end-effector which amplifies this motion and applies it to tissue being operated on. Ultrasonic vibration is induced in the surgical end-effector, for example, by electrically exciting a transducer which may be constructed of one or more piezoelectric or magnetostrictive elements in the instrument handpiece. Vibrations generated by the transducer section are transmitted to the surgical end-effector via an ultrasonic waveguide or blade extending from the transducer section to the surgical-end effector.
The ultrasonic waveguide or blade is typically formed as a solid core shaft which is machined from a monolithic piece of a titanium or aluminum alloy. If the device is constructed with multiple parts, the multiple parts are joined at antinodes, which are points of low vibrational stress, with joints extending substantially perpendicular to the longitudinal axis of the device. These devices are usually machined from larger pieces of metal, making them quite expensive to manufacture.
Reducing features and/or stock size can reduce the amount of machining required to form an ultrasonic waveguide or blade. However, most machining is performed on a lathe, such that the material and amount of machining is dictated by the maximum feature size. An ultrasonic waveguide or blade with a 1 cm lateral feature would generally require stock with a minimum of 2 cm diameter, even if the final part is only a few millimeters thick at any point. Moreover, any internal features of the ultrasonic waveguide or blade must be created with “line of sight” methods (i.e., drilled holes are possible, but S-shaped channels are not).